docs: def _load(self, time_series):
          """
          Load time series into a TimeSeries object.
          :param timeseries: a TimeSeries, a dictionary or a path to a csv file(str).
          :return TimeSeries: a TimeSeries object.
          """
          if isinstance(time_series, TimeSeries):
              return time_series
          if isinstance(time_series, dict):
              return TimeSeries(time_series)
          return TimeSeries(utils.read_csv(time_series))